pcspk.h

/* ScummVM - Graphic Adventure Engine
 *
 * ScummVM is the legal property of its developers, whose names
 * are too numerous to list here. Please refer to the COPYRIGHT
 * file distributed with this source distribution.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

#ifndef AUDIO_SOFTSYNTH_PCSPK_H
#define AUDIO_SOFTSYNTH_PCSPK_H

#include "audio/audiostream.h"
#include "common/mutex.h"
#include "common/queue.h"

namespace Audio {

class PCSpeaker : public AudioStream {
public:
    enum WaveForm {
        kWaveFormSquare = 0,
        kWaveFormSine,
        kWaveFormSaw,
        kWaveFormTriangle,
        kWaveFormSilence
    };

protected:
    // PC speaker instruction: play this waveform at frequency x for y microseconds.
    struct Command {
        WaveForm waveForm;
        float frequency;
        uint32 length;

        Command(WaveForm waveForm, float frequency, uint32 length);
    };

public:
    PCSpeaker(int rate = 44100);
    ~PCSpeaker();

    void play(WaveForm wave, int freq, int32 length);
    void playQueue(WaveForm wave, float freq, uint32 lengthus);
    void stop(int32 delay = 0);
    void setVolume(byte volume);

    bool isPlaying() const;

    int readBuffer(int16 *buffer, const int numSamples);

    bool isStereo() const   { return false; }
    bool endOfData() const  { return false; }
    bool endOfStream() const { return false; }
    int getRate() const { return _rate; }

protected:
    Common::Mutex _mutex;

    int _rate;
    WaveForm _wave;
    bool _playForever;
    uint32 _oscLength;
    uint32 _oscSamples;
    uint32 _remainingSamples;
    uint32 _mixedSamples;
    byte _volume;

    // The queue of playback instructions.
    Common::Queue<Command> *_commandQueue;
    // True if a playback instruction is currently being executed. False if
    // current playback was started by the play method (or if there is no
    // playback at all).
    bool _commandActive;

    typedef int8 (*generatorFunc)(uint32, uint32);
    static const generatorFunc generateWave[];

    static int8 generateSquare(uint32 x, uint32 oscLength);
    static int8 generateSine(uint32 x, uint32 oscLength);
    static int8 generateSaw(uint32 x, uint32 oscLength);
    static int8 generateTriangle(uint32 x, uint32 oscLength);
    static int8 generateSilence(uint32 x, uint32 oscLength);
};

} // End of namespace Audio

#endif // AUDIO_SOFTSYNTH_PCSPEAKER_H